It is common practice to manufacture heat exchangers for exchanging heat between fluids in which inner and outer tubes are arranged in coaxial relationship to provide a cylindrical space between them which serves as a flow space for one of the fluids and occupied by a fluid agitator or turbulator and to provide fittings at each end of the outer tube for directing a fluid into and out of the space while a second fluid flows through the interior of the inner tube. Heat exchangers of this type are disclosed in Dedo U.S. Pat. No. 2,752,125 assigned to the same assignee as the present application and Straubing U.S. Pat. No. 3,001,767.
The applicant here has discovered that this type of heat exchanger can be made readily, efficiently and at less cost by the method of this invention and the resulting heat exchangers have advantages not achieved by those of the prior art.